(1) Field of the Invention
My invention relates to chuck jaws usable as a holder for a workpiece, and more particularly to an improvement in chuck jaws which are customarily hardened to increase the durability thereof.
(2) Description of the Prior Art
It has long been known in the prior art to employ chuck jaws as the means by which a workpiece is held, while some form of work operation is being performed thereon. Any such chuck jaw must meet a multiplicity of requirements. For instance, the chuck jaw must include a gripping portion which is suitably configured so as to be compatible with the shape of the workpiece whereby to ensure that a secure grip is capable of being established between the chuck jaw and the workpiece.
Secondly, the chuck jaw should be sufficiently durable so as to be capable of satisfactorily resisting the wear and tear to which the chuck jaw is subjected while functioning as a holder for a workpiece. Commonly, the chuck jaw, after machining, is hardened to increase the durability thereof.
Thirdly, it is desirable that the chuck jaw be reusable, if possible. The term reusable as used herein refers to the chuck jaw's ability to be subsequently used with other workpieces of differing shapes, in addition to the chuck jaw's ability to be used repetitively with workpieces which embody substantially identical gripping surfaces.
Heretofore, it has been found that the prior art most often has employed chuck jaws which are of one piece construction. Moreover, such chuck jaws are commonly made of soft steel. This enables the chuck jaw to be cut and shaped, i.e., machined, to fit the requirements of the particular application in which it is desired to utilize the chuck jaw. Often, chuck jaws of one piece construction are not hardened. Consequently, one finds that the life of the chuck jaw is relatively short. The reason for this is that once hardened the chuck jaw is virtually unmachinable.
Insofar as concerns reusability of the chuck jaw, the prior art practice has been to recut and reshape the chuck jaw to meet other applications as the need therefor arises. At some point however, the chuck jaw is no longer susceptible to being recut and reshaped. Therefore, the chuck jaw must be discarded. Because of this need to recut and reshape the chuck jaw, the latter is not hardened, i.e., the chuck jaw can not be hardened, if it is desired to be able to subsequently recut and reshape the chuck jaw.
It can thus be seen that prior art chuck jaws have commonly suffered from one or the other of two major disadvantages. Namely, in those instances wherein the chuck jaw has been hardened following shaping to improve the durability thereof, the potential for reusability of the chuck jaw has been significantly restricted. On the other hand, in those instances wherein the chuck jaw has not been hardened in order to increase its potential for reuse, the life of the chuck jaw has been significantly shortened by virtue of the fact that the chuck jaw has not been hardened in an effort to increase the durability thereof.
There has thus existed a need to provide a chuck jaw which does not suffer from either of the two significant disadvantages.